1. Field of the Invention
The present invention relates to a recording medium and a recording and reproducing apparatus, and more particularly to a multilayer recording medium having a plurality of recording layers for recording information by multi-photon absorption in a laminated direction, and a recording and reproducing apparatus compatible with the multilayer recording medium.
2. Description of the Related Art
In recent years, as the capacity of a recording medium is increased, there has been developed an optical recording medium having a plurality of recording layers in a laminated direction. For instance, the optical recording medium may have an arrangement that the plurality of recording layers and one servo layer are laminated. In this recording medium, a flat recording layer without a guide track is formed, and a servo layer having a guide track is formed on the recording layer. In this arrangement, in performing a recording/reproducing operation, a focusing servo signal and a tracking servo signal are generated based on the guide track formed in the servo layer. Controlling the position of a beam spot on the recording layer based on the servo signals allows the beam spot to scan the recording layer along an intended scanning trajectory.
The recording medium having the above arrangement is advantageous in increasing the capacity of the recording medium by increasing the number of recording layers to be laminated. On the other hand, however, increasing the number of recording layers to be laminated may result in increasing the distance between a servo layer and a recording layer in the laminated direction. As a result, a relation between the recording layer and the servo layer may become weak, and reliability of a servo signal with respect to the recording layer may be lowered. Thus, the recording medium has a limit on the number of recording layers to be laminated, which resultantly restricts the recording capacity.